In human genetic variation, which specific DNA point mutation in the HBB (β-globin) gene causes sickle cell anemia?

• A. A splice-site mutation in an intron that prevents proper removal of the intron and eliminates β-globin production
• B. A frameshift mutation caused by a single-nucleotide insertion near codon 6 that alters the reading frame
• C. A missense mutation that changes codon 6 from GAG (glutamic acid) to GTG (valine)
• D. A nonsense mutation that changes codon 6 from GAG to TAG, creating a premature stop codon

Answer: (C)